1. Field of the Invention
The present invention relates to a scale mechanism for weighing either animate or inanimate objects as they are moved across a scale platform.
2. Description of the Related Art
Scales for weighing moving objects such as livestock, wheeled vehicles, or packages moving along a conveyor line generally include a weighing platform across which the object moves as it is being weighed. (As used herein the term xe2x80x9cplatformxe2x80x9d can include a section of rail or track, a tube, or any structure across or through which an item to be weighed can be moved.) The weighing platform is connected to a weighing device such as a spring scale, balance, or load cell for measuring the weight acting on the platform. Prior art scales have attempted to suspend the platform in such a manner that the weighing device can register all of the weight on the platform, no matter where the object is positioned on the platform. Scales of this type have a major disadvantage in that any shock loads acting on the platform are transferred to the weighing device. Shock loads primarily occur when the object is placed on or enters the platform and when the object is removed from the platform. When the load being weighed comprises live animals, shock loads can also occur as the animal moves about on the platform. Shock loads transmitted to the weighing device cause erratic readings to be registered by the weighing device and thereby cause inaccuracy of the weight measurement. Shock loading can also damage the weighing device and lead to its premature failure.
What is needed is a scale mechanism which isolates the weighing device from the majority of shock loads so that accurate weight readings can be obtained.
The present invention comprises a scale for weighing moving objects in which the weight of the object is gradually transferred onto the weighing device and then gradually transferred off of the weighing device after a weight measurement is taken. The scale drastically reduces shock loading of the weighing device. The scale includes a weighing platform having an entrance end and an exit end. The platform is connected to a tipping balance member having a first end and a second end. The tipping balance member is mounted for pivotal rotation about a fulcrum intermediate the first and second ends. The tipping balance member is connected to the weighing platform such that downward movement of the platform entrance end causes the tipping balance member to pivot in a first direction and downward movement of the platform exit end causes the tipping balance member to pivot in a second direction opposite the first direction. A weighing device is operatively connected to the fulcrum so as to measure weight acting on the fulcrum. A first limit stop is positioned to limit movement of the tipping balance member in the first direction. Similarly, a second limit stop is positioned to limit movement of the tipping balance member in the second direction.
As a load enters the platform from the entrance end, its weight initially pushes downwardly on the entrance end and thereby pivots the tipping balance member in the first direction and against the first limit stop such that a portion of the weight bears against the first limit stop. As the load continues across the platform its weight gradually shifts from the entrance end of the platform to the exit end. As the weight is redistributed, the tipping balance member pivots in the second direction and off of the first limit stop. Once the tipping balance member clears the first limit stop, the weighing device can measure the weight of the load. As the load continues to move toward the exit end of the platform, a sufficient portion of the weight shifts to said exit end to move the exit end downwardly. Downward movement of the exit end causes the tipping balance member to pivot in the second direction and against the second limit stop such that a portion of the weight bears against the second limit stop. The weight of the load is then gradually transferred from the fulcrum to the second limit stop until the load exits the platform.